Mallet Finger

Anatomy

Ilustration by Dr. Lisa Bryski

A Mallet fracture is a partial tear or complete rupture of the extensor tendon at the distal interphalangeal (DIP) joint.³

Lacerations/abrasions of the tendon and fractures of the distal phalanx at the tendon's insertion can also create the mallet posture.¹ Often described as soft or bony. Bony referring to an associated fracture and soft with no fracture.

classic presentation

Caused by a direct blow to the fingertip while the DIP joint is in active extension. The patient experiences pain and inability to extend the DIP joint.

Often occurs during any contact sports in which the finger is subjected to force from a ball, a fall or another player.²

diagnosis

Diagnosed based on:

history
physical exam
x-ray to rule out bony injuries

The physical exam will reveal an extensor lag of the DIP. The examiner may also notice hyperextension at the PIP, a compensatory swan neck deformity.¹

Clinical Tip: The most classic feature is the inability to extend the DIP joint fully. Therefore, the DIP is flexed at rest.

The "Doyle Classification" is used to classify mallet fingers:

Type 1: closed injury to the finger +/- dorsal avulsion facture
Type 2: open injury (superficial laceration at DIP)
Type 3: open injury (deep abrasion with skin/extensor tendon loss)
Type 4:
- A: growth plate fracture (pediatrics)
- B: fracture fragment involving 20% to 50% of articular surface (adult)
- C: fracture fragment >50% of articular surface (adult)

management

The goal of management is to restore active DIP joint extension. Most mallet fingers are treated non-surgically by splinting, with the main challenge being patient compliance.

Splinting is also preferred over surgery in cases of delayed presentation (>15 days). The splint should be bent slightly to stabilize the DIP joint in 5 to 10 degrees of hyperextension.

The mean length of continuous immobilization required is around 6 weeks and adherence is essential. The DIP joint must be maintained in full extension throughout the entire period, including during sleep.

On the other hand, surgical treatment is preferable in cases with volar subluxation and fractures involving >1/3 of the articular surface.³

References

Miller, M. D., Hart, J., & MacKnight, J. M. (2019). Essential Orthopaedics E-Book. Elsevier Health Sciences.
Bachoura, A., Ferikes, A. J., & Lubahn, J. D. (2017). A review of mallet finger and jersey finger injuries in the athlete. Hand and Wrist Sports Medicine, 1–9.
Lin, J. S., & Samora, J. B. (2020). Surgical and Nonsurgical Management of Mallet Finger: A Systematic Review. Journal of Hand Surgery, 43(2), 146–163.e2.

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